Drilling fluid or mud is used in drilling operations, such as oil well drilling, by circulating the drilling fluid in the hole being drilled for contact with the drill bit to cool and lubricate the bit. In addition, the drilling fluid serves to carry away drill cuttings from the hole and seals porous strata from drilling fluid or mud penetration.
One commercially acceptable drilling fluid or mud comprises a dispersion of sodium bentonite in water. The sodium bentonite portion of this type of drilling fluid raises the viscosity and yield point of the drilling fluid. The purpose of increasing the viscosity is so that the drilling fluid is more able to raise the cuttings to the surface where the cuttings can be removed by means of screens and the like. Other additives have been included in sodium bentonite type drilling fluids oftentimes in an attempt to prevent loss of the circulated drilling fluid through the porous surfaces surrounding the drill hole.